Wireless transmitting/receiving method and wireless transmitting/receiving apparatus

ABSTRACT

It is an object of the present invention to provide a wireless transmitting/receiving method for achieving both a high-speed data transfer and a power-saving operation by using wireless transmitting/receiving apparatus adaptable to a ubiquitous system, whereby a wireless transmitting/receiving method which performs wireless transmission/reception using no less than two carrier waves which belong to a different frequency band is used to transmit/receive a control signal for controlling the transmission/reception operation of the wireless transmitting/receiving apparatus by using a carrier wave which belongs to a lower frequency band (400 MHz band), and to transfer data by using a carrier wave which belongs to a higher frequency band (2.4 GHz band).

This application is the National Phase of PCT/JP2006/316860, filed Aug.28, 2006, which claims priority to Japanese Application No. 2005-283842,filed Sep. 29, 2005, the disclosures of which are hereby incorporated byreference in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless transmitting/receivingapparatus for performing data exchange by performing wirelesstransmission/reception to and from a transmitting/receiving apparatus ofa communication counterpart, and particularly to a wirelesstransmitting/receiving method for controlling the wirelesstransmission/reception performed between the wirelesstransmitting/receiving apparatuses.

BACKGROUND ART

As semiconductor microprocessing technology advances, wirelesscommunication devices and apparatuses are stably supplied at a low costand in a large quantity, becoming widespread in daily life. From now on,it is expected that a ubiquitous era will arrive when wirelesscommunication devices are mounted on every entity. Since wirelesscommunication devices in such ubiquitous era need to operate for longhours on a battery, reduction of the power consumption thereof hasbecome an essential technology.

As one example of such wireless communication devices, a wireless devicespecification as shown in Non-patent Document 1 has been proposed. InFIG. 1 of Non-Patent Document 1, a configuration is shown in which anetwork is formed between wireless communication devices and in whichdata acquired by each device is sent to a server (a PAN coordinator).Also, in Patent Document 1, there is demonstrated a system in which awireless communication device respectively mounted on a room temperaturesensor, an air conditioner, and a hot-water supply apparatus transmitsits state/operation to an external communication line, and therespective operational state is transferred by external means ofcommunication to an external communication line. Further, in PatentDocument 2, it is shown that a different frequency is used duringtransmission and during reception in a wireless communication device.

However, in the wireless communication systems disclosed in the abovedescribed Patent Document 1, Patent Document 2, and Non-patent Document1, a problem exists in that a high-speed data communication and apower-saving operation are not consistent with each other. This isbecause the maximum transmitting/receiving rate of a wirelesscommunication device is determined by the frequency band of the carrierwave to be used, while the power consumption thereof significantlydepends on the frequency of the carrier wave.

That is, when performing a high-speed data communication such as imagetransfer, it is necessary to use a high frequency band such as a 5 GHzband or 2.4 GHz band; however, in order to extract data communicated insuch a band from the carrier wave or to superimpose communication dataon the carrier wave, a circuit which operates at a high-speed such as of5 GHz or 2.4 GHz in the wireless communication device is necessary andsuch high-speed operation circuit part will consume the bulk of thepower required for the wireless communication device.

Generally, in a wireless communication system, as shown in FIG. 1, acarrier wave of a single frequency band which is allocated by legalregulation such as a radio law is used to perform thetransmission/reception of data and operational control. Therefore, themaximum transmission/reception data rate is determined by the allocatedfrequency band.

In the related art described in Patent Document 2, although separatecarrier frequencies are used during transmission and during reception ofa wireless communication device, the difference between the carrierfrequencies is very small since it is based on the use of separatechannels in the same frequency band, and therefore the difference incarrier frequency caused by selecting of different channels has littleeffect on the operational power.

Further, in Non-patent Document 1, a mechanism such as an intermittentoperation is proposed to realize a low-power operation; however, in thissystem which utilizes a single frequency band, the total datacommunication amount will be reduced in proportion to the power decreasethat results from the intermittent operation.

In recent years, an ad hoc network system which is realized only byterminals communicating with each other has gained much attention. Thisad hoc network system is a system which is made up of, as shown in FIG.2, a plurality of terminals 91 and communicates information with otherterminals by exchanging transfer-data with each other on wirelesstransmission/reception signal 92 between terminals 91, the system beingcharacterized in that it is not restricted by an access area and needsno expensive facilities.

A wireless communication network system which utilizes an ad hoc meshnetwork is widely used in a security ensuring system that utilize amonitor camera network, an entrance/exit inspection system, a physicaldistribution management system, a patient management system in medicalfields, and the like.

Next, description will be made on a problem in the case in which awireless transmitting/receiving apparatus that utilizes only onefrequency band as shown in FIG. 1 is used as the terminal of the abovedescribed ad hoc network system.

First, a hidden terminal problem in an ad hoc wireless system will bedescribed with reference to FIG. 3. In FIG. 3, terminal B and terminal Care in communication, and when terminal A is not aware that terminal Bis in communication with terminal C, terminal A may send a communicationrequest to terminal B which is performing communication. However, sinceterminal A cannot receive any response from terminal B, thecommunication request operation of terminal A becomes a wasted operationthereby consuming power in effectually. A flow chart to describe thisoperation is shown in FIG. 4.

In FIG. 4, when terminal A issues a communication request to terminal B(step 111), since terminal B and terminal C are in communication,terminal A cannot receive a response from terminal B (step 112).Therefore, terminal A is on standby for a fixed time period (step 113)and thereafter again issues a communication request to terminal B (step114), thus repeating steps 115 and 116. These steps will be repeateduntil the communication between terminal B and terminal C is completed.Then, when communication between terminal B and terminal C is completed(steps 117 and 118), if terminal A will issues a communication requestto terminal B (step 119), terminal A receives a response from terminal B(step 120), and communication will be started.

FIG. 5 shows an exposed terminal problem in an ad hoc wireless system.FIG. 5 shows a situation in which although terminal C and terminal D arein communication, and terminal B is trying to perform a datatransmission to terminal A, since terminal B can perceive thecommunication of terminal C, it cannot go into transmission operationand cannot perform data transmission to terminal A. A flow chart to showthis operation will be shown in FIG. 6.

When terminal B wants a communication with terminal A (step 131),terminal B inevitably detects the communication carrier of terminal C(step 132). Then, terminal B is on standby for a fixed period of time(step 133), and thereafter detects the communication carrier of terminalC (step 134) when again determining the presence or absence of thecommunication carrier, thus coming into standby operation (step 135).Then, this step is repeated until communication between terminal C andterminal D is completed. Then, when communication between terminal C andterminal D is completed (steps 136 and 137), terminal B confirms theabsence of communication carrier (step 138), and is then allowed toissue a communication request to terminal A (step 139).

Thus, when an ad hoc network system is configured by using aconventional wireless transmitting/receiving apparatus, uselesscommunication processing will be repeated and thereby transmission powerwill be wasted.

Further, a typical wireless communication system has a problem in whichthe time period of reception standby will be longest for each terminal,and when a high-frequency carrier frequency band is used in order torealize a high speed operation by increasing the transmitting/receivingtransfer rate, it is necessary to operate a circuit for receiving a highcarrier frequency even for standby operation and thereby powerconsumption will be increased.

-   Patent Document 1: Japanese Patent Laid-Open No. 2001-101578-   Patent Document 2: Japanese Patent Laid-Open No. 10-13958-   Non-patent Document 1: IEEE Computer Society, 804.15.4, Part 15.4:    Wireless Medium Access Control (MAC) and Physical Layer (PHY)    Specifications for Low-Rate Wireless Personal Area Networks    (LR-WPANs)

In the conventional transmitting/receiving apparatus described above, aproblem exists in which high-speed data communication and a power-savingoperation cannot be achieved at the same time.

It is an object of the present invention to provide a wirelesstransmitting/receiving apparatus and a wireless transmitting/receivingmethod which enables realizing both high-speed data communication and apower-saving operation.

DISCLOSURE OF THE INVENTION

In order to achieve the above described object, the wirelesstransmitting/receiving method of the present invention is a wirelesstransmitting/receiving method for performing wirelesstransmission/reception using no less than two carrier waves which belongto a different frequency band, comprising the steps of:

transmitting/receiving a control signal for controlling thetransmission/reception operation of a wireless transmitting/receivingapparatus, by using a carrier wave which belongs to a lower frequencyband; and

transferring data by using a carrier wave which belongs to a higherfrequency band.

Moreover, the above described control signal may include a signal forperforming authentication processing of a communication counterpart.

Further, the transmitting/receiving method of the present invention mayfurther comprise the steps of:

performing power adjustment to reduce the transmission power of acommunication using a lower frequency band and, when the communicationof the lower frequency band is disabled, performing transmission poweradjustment of the communication that uses the lower frequency band byincreasing the transmission power of the communication using the lowerfrequency band by means of a communication that uses higher frequencyband; and

performing power adjustment for reducing the transmission power of acommunication using a higher frequency band and, when the communicationof the higher frequency band is disabled, performing transmission poweradjustment of the communication that uses the higher frequency band byincreasing the transmission power of the communication using the higherfrequency band by means of a communication that uses the lower frequencyband.

According to the present invention, it becomes possible to achieve botha high-speed data communication and a power-saving operation bytransmitting/receiving a control signal such as a signal for performingauthentication processing using a carrier wave which belongs to a lowerfrequency band which consumes less power, and after a communicationcounterpart is determined, transferring data using a carrier wave whichbelongs to a higher frequency band by which a maximumtransmission/reception rate may be set at a high value.

By this arrangement, it is possible to reduce power consumption byperforming communication using a lower frequency band during signalreception standby period which occupies the bulk of the operation in aubiquitous wireless system, and to enable high-speed data communicationby performing communication using a higher frequency band whenperforming active communication.

As so far described, according to the present invention, it is possibleto achieve an effect in which high-speed data communication and alow-power consumption operation can be achieved at the same time bytransmitting/receiving control signals by using a carrier wave whichbelongs to a lower frequency band which consumes less power, and bytransferring data by using a carrier wave which belongs to a higherfrequency band in which a higher maximum transmission/reception rate canbe set.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a network connection protocol example according to aconventional wireless transmitting/receiving method;

FIG. 2 is a conceptual diagram to show an ad hoc network connection;

FIG. 3 is a conceptual diagram to describe a hidden terminal problem inan ad hoc network;

FIG. 4 is a flow chart to describe a conventional operation under ahidden terminal environment in an ad hoc network;

FIG. 5 is a conceptual diagram to describe an exposed terminal problemin an ad hoc network;

FIG. 6 is a flow chart to describe a conventional operation in anexposed terminal environment of an ad hoc network;

FIG. 7 is a conceptual diagram to show a communication form betweenwireless apparatuses which use the wireless transmitting/receivingmethod according to an exemplary embodiment of the present invention;

FIG. 8 shows an example of the wireless transmitting/receiving apparatusto implement the wireless transmitting/receiving method according to anexemplary embodiment of the present invention,

FIG. 9 shows an example of the network protocol which uses the wirelesstransmitting/receiving method according to an exemplary embodiment ofthe present invention;

FIG. 10 is a flowchart to show processing in the case in whichauthentication in a 400 MHz band is not performed in the wirelesstransmitting/receiving method according to an exemplary embodiment ofthe present invention;

FIG. 11 is a flowchart to show processing in the case in whichauthentication in a 400 MHz band is performed and power adjustment ofthe 400 MHz band is performed with 2.4 GHz band communication beingestablished in the wireless transmitting/receiving method according toan exemplary embodiment of the present invention;

FIG. 12 is a flowchart to describe the operation according to thepresent invention under a hidden terminal environment in an ad hocnetwork; and

FIG. 13 is a flowchart to describe the operation according to thepresent invention under an exposed terminal environment in an ad hocnetwork.

DESCRIPTION OF SYMBOLS

-   1 Filter-   2 2.4 GHz band transmitting/receiving part-   3 Authentication and power control part-   4 Filter-   5 400 MHz band transmitting/receiving part-   6 Reception control signal-   7 Transmission control signal-   8 2.4 GHz band transceiver part operation control signal-   41-46 Step-   51-63 Step-   71-76 Step-   81-86 Step-   91 Terminal-   92 Wireless transmission/reception signal-   111-120 Step-   131-139 Step

BEST MODE FOR CARRYING OUT THE INVENTION

Next, exemplary embodiments of the present invention will be describedin detail with reference to the drawings. Here, by way of simplicity,description will be made on the simplest case in which there are twofrequency bands. The term “frequency band” used herein refers to afrequency range which is individually defined based on legal regulationrelating to radio usage, typified by radio law, and based on a standardspecification.

FIG. 7 shows the manner in which communication is performed betweenwireless communication devices according to the present embodiment.Between node A and node B which make up a network, communication isbeing performed using both a lower frequency band (a 400 MHz band inthis case) and a higher frequency band (a 2.4 GHz band in this case).

Next, a specific configuration example of the wirelesstransmitting/receiving apparatus as shown in FIG. 7 will be shown inFIG. 8. This wireless transmitting/receiving apparatus comprises filters1 and 4, 2.4 GHz band transmitting/receiving part 2, 400 MHz bandtransmitting/receiving part 5, and authentication and power control part3.

2.4 GHz band transmitting/receiving part 2 for transmitting/receiving asignal provided by a carrier wave belonging to a 2.4 GHz band which is ahigher frequency band.

400 MHz band transmitting/receiving part 5 for transmitting/receiving asignal provided by a carrier wave belonging to a 400 MHz band which is alower frequency band.

Authentication and power control part 3 exchanges a control signal forcontrolling a transmission/reception operation such as an authenticationprocessing with a communication counterpart using 400 MHz bandtransmitting/receiving part 5, and when a communication counterpart isdetermined, operates 2.4 GHz band transmitting/receiving part 2 toperform data transmission/reception to and from the communicationcounterpart.

In the transmitting/receiving apparatus in the present embodiment, asshown in FIG. 8, transmitting/receiving parts 2, 5 which correspond to aplurality of carrier frequencies, are provided in the same apparatus.The higher frequency circuit (2.4 GHz band transmitting/receiving part 2in this case), which consumes more power, is adapted to operate onlywhen the reception of the lower frequency circuit (400 MHz band) isqualified. In the example of FIG. 8, signal 6 received by 400 MHz bandtransmitting/receiving part 5 is analyzed at authentication control part3, and when determined that it is a signal transmitted from a normalcounterpart, authentication control part 3 outputs response signal 7 forthe communication counterpart to 400 MHz band transmitting/receivingpart 5. Then, authentication control part 3 outputs 2.4 GHz bandtransceiver part operation control signal 8 for activating thepower/clock signal generation of 2.4 GHz band transmitting/receivingpart 2 to enable the transmission/reception in the 2.4 GHz band.Therefore, 2.4 GHz band transmitting/receiving part 2, which is ahigh-frequency band circuit, operates only intermittently, and thus theneed of continuous operation of 2.4 GHz band transmitting/receiving part2, which is necessary when directly receiving a 2.4 GHz band signal, isobviated thereby enabling to suppress power consumption. Further, in thewireless transmitting/receiving apparatus of the present embodiment,when high-speed communication is actively performed, an authenticationsignal is transmitted from 400 MHz band transmitting/receiving part 5 toa counterpart node, and after the completion of authentication, 2.4 GHzband transmitting/receiving part 2 is operated so that a high-speed datacommunication is realized.

In the embodiment described above, the setting of 400 MHz bandtransmission/reception power and 2.4 GHz band transmission/receptionpower may be adaptively optimized.

For example, authentication control part 3 performs power adjustment toreduce the transmission power of the communication which uses a 400 MHzband and, when the communication in the 400 MHz band is disabled,performs transmission power adjustment of the communication using 400MHz band by increasing the transmission power of the communication whichuses the 400 MHz band, by means of the communication that uses the 2.4GHz band.

Further, authentication control part 3 performs power adjustment toreduce the transmission power of the communication which uses the 2.4GHz band and, when the communication of 2.4 GHz band is disabled,performs transmission power adjustment of the communication which usesthe 2.4 GHz band by increasing the transmission power of thecommunication which uses the 2.4 GHz band, by means of the communicationthat uses the 400 MHz band.

The procedure for thus adaptively optimizing the setting of 400 MHz bandtransmission/reception power and the 2.4 GHz band transmission/receptionpower is shown in FIG. 9. Network connection between nodes shown in FIG.7 is first started from the 400 MHz band. In the firsttransmission/reception of the 400 MHz band, data transmission/receptionis performed after performing initialization processing such aspreamble, carrier sense, synchronization, and authentication processing.Here, by arranging a configuration such that communication in the 2.4GHz band is performed only with a communication counterpart which canperform normal authentication processing in 400 MHz band, ensuringsecurity in 2.4 GHz band communication is made possible. Further, sinceperforming authentication in the 400 MHz band obviates the need forusing the 2.4 GHz band for the communication from a communicationcounterpart other than approved communication counterpart, it ispossible to reduce the frequency of the high-frequency communicationoperation which consumes much power. Further, by using atransmission/reception device comprising a mutually independenttransmitting/receiving apparatus respectively for the 400 MHz band andthe 2.4 GHz band, it is possible to implement transmission/reception of400 MHz band and 2.4 GHz band in parallel.

As shown in FIG. 9, power adjustment of the 400 MHz bandtransmitting/receiving apparatus can be performed in parallel whileperforming transmission/reception in the 2.4 GHz band. FIG. 10 shows theprocessing in the case in which authentication in the 400 MHz band hasnot been performed, and FIG. 11 shows processing in the case in whichauthentication in the 400 MHz band has been performed, and poweradjustment of the 400 MHz band is performed with a 2.4 GHz bandcommunication being established.

First, description will be made of the operation when authentication isnot performed, with reference to FIG. 10. In this case, terminal Aissues a communication request to terminal B at a maximum power using afrequency of the 400 MHz band (step 41). Having received thiscommunication request from terminal A, terminal B makes a response toterminal A at a maximum power using a frequency of the 400 MHz band(step 42). Thereafter, mutual authentication is performed betweenterminal A and terminal B using a frequency of the 400 MHz band (step43). However, in this case, since authentication result will be “NG”(step 44), terminals A and B interrupt communication and end thecommunication (steps 45 and 46).

Next, referring to FIG. 11, description will be made of the operationwhen authentication in the 400 MHz band is performed and poweradjustment of 400 MHz band is performed with 2.4 GHz band communicationbeing established. In this case, terminal A issues a communicationrequest to terminal B at a maximum power using a frequency in the 400MHz band (step 51). Having received the communication request fromterminal A, terminal B makes a response to terminal A at a maximum powerusing a frequency in the 400 MHz band (step 52). Thereafter, mutualauthentication is performed between terminal A and terminal B using afrequency in the 400 MHz band (step 53). The processing so far describedis the same as that in the flowchart shown in FIG. 10.

However, here, since the authentication result will be “OK” (step 54),terminal A issues a communication request to terminal B at a maximumpower using a frequency of the 2.4 GHz band (step 55). Then, havingreceived the communication request from terminal A, terminal B makes aresponse to terminal A at a maximum power using a frequency of the 2.4GHz band (step 56).

Thus, with communication in the 2.4 GHz band being established,terminals A and B perform power adjustment of a frequency of the 400 MHzband (steps 57 to 59). When communication between terminals A and Bhaving a frequency of the 400 MHz band is interrupted by this poweradjustment (step 60), terminal A issues a request for an increase in thepower of the frequency of the 400 MHz band to terminal B through afrequency of the 2.4 GHz band (step 61). Similarly, terminal B issues arequest for an increase in the power of a frequency of the 400 MHz bandto terminal A through a frequency of the 2.4 GHz band (step 62). Thus,the power of a frequency of the 400 MHz band between terminals A and Bis adjusted to be a minimum power for enabling communication (step 63).

In FIG. 11, it is shown that the initial connection is performed at amaximum power for both the 400 MHz band and the 2.4 GHz band, andadjustment is performed to gradually decrease the power of the 400 MHzband. Since, as power decreases, the communicable distance decreases andthe S/N ratio declines, communication in the 400 MHz band is interruptedat a certain point. At this time, by increasing processing power byusing the 2.4 GHz band that is being used for communication, a 400 MHzband communication is established having the required, sufficient power.In the wireless transmitting/receiving method according to the presentembodiment, even when the power of the transmitting/receiving equipmentis excessively decreased resulting in an interruption of the 400 MHzband communication, since communication using the 2.4 GHz band can becontinued to confirm the state of each node with each other, the need ofsynchronization and authentication processing, etc. between wirelesscommunication devices is obviated. Consequently, when establishingcommunication in the 400 MHz band again, it is possible to drasticallysimplify and shorten the above described initialization processing.Therefore, compared with the conventional example shown in FIG. 1, thepower adjustment of the 400 MHz band can be completed very rapidly.

Similarly, performing power adjustment of the 2.4 GHz band after thecompletion of the power adjustment of the 400 MHz band enablescommunication at a minimum power in each frequency band.

Further, as shown in FIG. 10, since when authentication processingcannot be performed in the 400 MHz band, the wirelesstransmitting/receiving apparatus of the 2.4 GHz band, which consumesmore power, will not be operated, it is possible to avoid wasteful powerconsumption.

Furthermore, it is possible to realize a wireless transmitting/receivingmethod by which a low-power operation is made possible in the timeperiod of the standby operation for signal reception, which occupies thebulk of the operation time period of a ubiquitous system, and high-speeddata transfer can be performed during a spontaneous active operation.

Next, description will be made of the operation when such wirelesstransmitting/receiving apparatus is applied to the ad hoc network systemshown in FIG. 2.

In an ad hoc network system made up of a conventional wirelesstransmitting/receiving apparatus which utilizes only one frequency band,as described above, the hidden terminal problem and the exposed terminalproblem shown in FIGS. 3 and 5 take place. However, by using a wirelesstransmitting/receiving apparatus which utilizes two frequency bands suchas the wireless transmitting/receiving apparatus of the presentembodiment, solving these problems is made possible thereby reducingpower consumption.

In the wireless transmitting/receiving apparatus of the presentembodiment, since even under a hidden terminal environment in whichterminal B and terminal C are in communication using a frequency of the2.4 GHz band as shown in FIG. 3, terminal B can receive a communicationrequest which utilizes a frequency of the 400 MHz band from terminal A,and terminal B can return a response signal to terminal A. Theoperations of terminals A, B, and C at this time are shown in FIG. 12.

First, terminal A issues a communication request to terminal B using afrequency of the 400 MHz band (step 71). At this time, even if terminalB and terminal C are in communication using a frequency of the 2.4 GHzband, terminal B can transmit a response signal to terminal A.Therefore, terminal A can learn that terminal B is in communication withterminal C, thereby terminal A comes into a standby state (step 72). Andwhen the communication between terminal B and terminal C is completed(steps 73 and 74), terminal A issues a communication request to terminalB and receives a response signal from terminal B to start communicationwith terminal B using a frequency of the 2.4 GHz band (step 76).

Since thus terminal B can notify terminal A of the fact that it is incommunication, and of the communication time period of the ongoingcommunication etc., terminal A is prevented from making a uselesscommunication request. As a result of this, the problem of powerincrease due to useless operation of terminal A will be solved.

Further, in the wireless transmitting/receiving apparatus of the presentembodiment, even in the case of an exposed terminal problem as shown inFIG. 5 in which terminal C and terminal D are communicating in 2.4 GHz,terminal B can issue a communication request using the 400 MHz band toterminal A to establish communication between terminal B and terminal A.The operations of terminals A, B, C and D at this time are shown in FIG.13.

First, when terminal B wants to established communication with terminalA (step 81), although terminal B detects the signal of the 2.4 GHzcommunication carrier of terminal C (step 82) by confirming the signalsof communication carriers that can be received, it confirms that thereis no signal from communication carrier having a 400 MHz (step 83).Therefore, terminal B issues a communication request to terminal A usinga frequency of the 400 MHz band (step 84). Then, terminal B receives aresponse signal using a frequency of the 400 MHz band from terminal A toperform communication.

Then, when communication between terminal C and terminal D using afrequency of the 2.4 GHz band is completed (steps 85 and 86), terminal Aand terminal B start communication using a frequency of the 2.4 GHzband.

INDUSTRIAL APPLICABILITY

Thus, according to the wireless transmitting/receiving method of thepresent embodiment, the hidden terminal problem and the exposed terminalproblem, which cause a problem in an ad hoc network made up ofconventional wireless transmitting/receiving apparatuses, have beensolved. As a result, the frequency at which uselesstransmitting/receiving operations are performed decreases, and thepower-saving characteristics and the communication data rate of theentire network are improved.

That is, according to the wireless transmitting/receiving method of thepresent embodiment, by using two carrier frequencies to optimallycontrol the transmission/reception power at a high-speed for eachcarrier frequency, it is possible to cope with problems that arespecific to a ubiquitous ad hoc network, such as a hidden terminalproblem and an exposed terminal problem, and to realize the minimizationof power consumption during operation.

Further, since power during transmission/reception is minimized by usingcarrier waves of two frequency bands, which complies a higher frequencyband and a lower frequency band, a synergic effect is achieved byavoiding the problem caused by radio waves that reach parties with whichcommunication is not to be performed as shown in FIGS. 3 and 5.

Although, by way of simplicity, description has been made on the case inwhich two frequency bands are used, a 400 MHz band and a 2.4 GHz band,the present invention will not be limited to such case, and may besimilarly applied to the cases in which more than two frequency bandsare used.

1. A wireless transmitting/receiving method for performing wirelesstransmission/reception using no less than two carrier waves which belongto a different frequency band, comprising: transmitting/receiving acontrol signal for controlling the transmission/reception operation of awireless transmitting/receiving apparatus, by using a carrier wave whichbelongs to a lower frequency band; transferring data by using a carrierwave which belongs to a higher frequency band; performing poweradjustment for reducing the transmission power of a communication usinga lower frequency band and, when the communication that uses a lowerfrequency band is disabled, performing transmission power adjustment ofthe communication using the lower frequency band by increasing thetransmission power of the communication using the lower frequency bandby means of a communication that uses the higher frequency band; andperforming power adjustment for reducing the transmission power of acommunication using a higher frequency band and, when the communicationthat uses the higher frequency band is disabled, performing transmissionpower adjustment of the communication using the higher frequency band byincreasing the transmission power of the communication using the higherfrequency band by means of a communication that uses the lower frequencyband.
 2. The wireless transmitting/receiving method according to claim1, wherein said control signal may include a signal for performingauthentication processing of a communication counterpart.
 3. A wirelesstransmitting/receiving apparatus, comprising: a firsttransmitting/receiving part for transmitting/receiving a signal providedby a carrier wave belonging to a first frequency band; a secondtransmitting/receiving part for transmitting/receiving a signal providedby a carrier wave belonging to a second frequency band which has ahigher frequency than that of said first frequency band; anauthentication control part for exchanging a control signal with acommunication counterpart for controlling the transmitting/receivingoperation using a carrier wave belonging to the first frequency band bycontrolling said first transmitting/receiving part, and when acommunication counterpart is determined, operating said secondtransmitting/receiving part to perform data transmission/reception toand from the communication counterpart; wherein said authenticationcontrol part performs power adjustment for reducing the transmissionpower of a communication using said first frequency band and when saidcommunication that uses the first frequency band is disabled, performstransmission power adjustment of the communication using said firstfrequency band by increasing the transmission power of the communicationusing said first frequency band by means of a communication that usessaid second frequency band; and wherein said authentication control partperforms power adjustment for reducing the transmission power of acommunication using said second frequency band and when saidcommunication that uses the second frequency band is disabled, performstransmission power adjustment of the communication using said secondfrequency band by increasing the transmission power of the communicationusing said second frequency band by means of a communication that usessaid first frequency band.
 4. The wireless transmitting/receivingapparatus according to claim 3, wherein said control signal includes asignal for performing authentication processing of a communicationcounterpart.
 5. A wireless transmitting/receiving method for performingwireless transmission/reception in a mesh network system using a radiowave for data transmission in terminals, and using no less than twocarrier waves which belong to a different frequency band, comprising:transmitting/receiving, within the mesh network system, a control signalfor controlling the transmission/reception operation of a wirelesstransmitting/receiving apparatus, by using a carrier wave which belongsto a lower frequency band, wherein said control signal may include asignal for performing authentication processing of a communicationcounterpart; and transferring data by using a carrier wave which belongsto a higher frequency band; performing power adjustment for reducing thetransmission power of a communication using a lower frequency band and,when the communication that uses a lower frequency band is disabled,performing transmission power adjustment of the communication using thelower frequency band by increasing the transmission power of thecommunication using the lower frequency band by means of a communicationthat uses the higher frequency band; and performing power adjustment forreducing the transmission power of a communication using a higherfrequency band and, when the communication that uses the higherfrequency band is disabled, performing transmission power adjustment ofthe communication using the higher frequency band by increasing thetransmission power of the communication using the higher frequency bandby means of a communication that uses the lower frequency band.
 6. Awireless transmitting/receiving apparatus in a mesh network system usinga radio wave for data transmission in terminals, comprising: a firsttransmitting/receiving part for transmitting/receiving a signal providedby a carrier wave belonging to a first frequency band; a secondtransmitting/receiving part for transmitting/receiving a signal providedby a carrier wave belonging to a second frequency band which has ahigher frequency than that of said first frequency band; and anauthentication control part for exchanging, within the mesh networksystem, a control signal with a communication counterpart forcontrolling the transmitting/receiving operation using a carrier wavebelonging to the first frequency band by controlling said firsttransmitting/receiving part, and when a communication counterpart isdetermined, operating said second transmitting/receiving part to performdata transmission/reception to and from the communication counterpart,wherein said control signal includes a signal for performingauthentication processing of a communication counterpart, wherein saidauthentication control part performs power adjustment for reducing thetransmission power of a communication using said first frequency bandand when said communication that uses the first frequency band isdisabled, performs transmission power adjustment of the communicationusing said first frequency band by increasing the transmission power ofthe communication using said first frequency band by means of acommunication that uses said second frequency band; and wherein saidauthentication control part performs power adjustment for reducing thetransmission power of a communication using said second frequency bandand when said communication that uses the second frequency band isdisabled, performs transmission power adjustment of the communicationusing said second frequency band by increasing the transmission power ofthe communication using said second frequency band by means of acommunication that uses said first frequency band.